Signaling system for railroads



Sept, 22, 1931. w. H. REICHARD SIGNALING SYSTEM FOR RAILROADS Filed July 23. 1929 I5 Sheets-Sheet l Sept. 22, 1931. w. H. REICHARD 1,824,173

l I SIGNALING SYSTEM FOR RAILROADS Filed July 23, 1929 3 Sheets-Sheet 2 A.C TRANSMISSION LINE\ FIGIZ.

w IWNT i SeptO 22,* 1931- w. H. REICHARD- SIGNALING SYSTEM FOR RAILROADS Filed July 23, 1929 3 Sheets-Sheet 3 lNvEN M YW' @2 ,Qi/0Min Patented Sept. 22, 1931 iran STATES PATENT omer:

WADE H. REICHARD, OF ROCHESTER, NEW YORK, ASSIGNOR TO'GENERAL RAILWAY p SIGNAL COMPANY, OF ROCHESTER, NEW YORK SIGNALING SYSTEM non RAILROADS Application led .Tuly 23, 1929. VSerial No. 380,346.

rihis invention rela-testo power interlocking systems for railroads, and more particu "1 points in the well known dynamic indication type of electric interlocking system.

1t has been proposed, as disclosed for eX- ample, in the application of William S.

Henry, Serial No. 139,641, filed October 5,

1926, to provide a relay in the tower, sometimes called a SS relay, which is controlled in accordance with the position and locked condition of the points of a track switch, and to utilize this SS relay as a means for check ing the relay and circuits affording crossprotection.

One object of the present invention is to provide an improved means of this character for controlling the circuit of the switch repeating or SS relay, so that its energization is dependent upon the operation of the control lever and the iow of dynamic indication current.

A further object is to control the switch repeating or SS relay in accordance with the position and locked condition of the switch points, by alternating current superimposed upon the regular operating or controlcircuits for the switch machine, so as to avoid the need for eXtra wires between the switch and the tower for theoperation of this SS relay, and also so as to afford an additional 1 check of the correspondence between the position of the switch points and its control lever.

In describing the invention in detail, reference will be made to the accompanying drawings, in which like reference characters `are used to designate like devices in the various figures, and in which,

Other features or functions of Vnormal position as shown. As soon as the Fig. 1 is a diagrammatic showing of one .specific embodiment of the present invention;

Fig. 2 is one modification of Fig. 1;

Fig. 3 is a second modification of Fig.A 1.

Referring to Fig. 1y of the drawings, the points of the track switch TS are connected tov and operated by a switch machine SM in ythe usual way, this switch machine SM being assumed to be of the type shown and described in the patent to W. K. Howe, No. 1,466,903, dated September 4, 1923. This switch machine SM comprises a direct currentmotor having'an armature A and a field F, and also includes two groups of contacts automatically operated in accordance with the position and locked condition of the switch machine SM.

One of these groups of contacts, conveniently called pole changer contacts and designated'PO, comprises four pairs of contact :wi fingers or springs and two movable contact blocks 5 and 6. These Contact blocks 5 and 6 are operated, in the manner shown and described in detail in the Howe patent above mentioned, by the gearing of the switch machine SM so as to be in one extreme position, as shown, when the switch machine is over and locked in that position, and to shift to the other extreme position, when the switch machine has operated and locked up in the other extreme position.

i The other group of contact-s, conveniently called point detector contacts and designated PD, are operated by the switch machine SM and additional connections to the switch points TS, in the manner as shown and described in detail, for example, in the patent to O. S. Bushnell, No. 1,507 ,236, dated November 25, 1924. These point detector contacts PD, comprise four pairs of contact fingers or springs and two movable Vcontact blocks 7 and 8. When the switch points TS are in the normal position as shown, and are locked, the contact blocks 7 and 8 are in the or, switch machine is unlocked, and as longas it is operating, these Contact blocks 7 and 8 are in the middle position, and do not engage with any of the pairs of contacts. When the switch points TS have been operated to the 10c reverse position and locked, the contact blocks 7 and 8 are shifted to the reverse position, opposite to that shown.

The point detector contacts PD are connected to the secondary of a local transformer 9, haVi-ngaseries resistance 1f0lfin: its secondary circuit,- and-a'lso preferablyzasseries resistance 11 in its primary circuit. This transformer 9 is supplied with alternating current lo 'from' apair vofwires, connected toa suitable alternating current source, andexterrdingbetween the tower and the switch.

In the interlocking tower, 'there is the usual manually operable controllever-L, hav- 15 ing contact members 12 and 13 engaging pairs :of contact lsprings in the' normal landxreverse position of this lever. This lever 1L; is preferably provided 'with 1 an @electricL lock (not shown), but does not have the iusualnfdica- 1 tion rmechanism and indication magnet.

Associated with" thei'lever: L-,is an electroresponsvie devicefIR, preferably of thefzconstruction of the indication selector iasshown Yand'i'described for example in the patent'l to y WV. -K.1Howe, 1,550,611, :dated AugustflS,

1925, `and comprises two coils 56 andl74 acting, whenialternately energized, toishift a movable 'contacti129f back fan'd forth` to `close circuits through the `stationary,contact and 30' the two contacts '28 and'87.

AlsoV associated withr the vlever-LV :isva crossprotection relay P of thexusual.constnuction,

such as shownand described-.for example in the f patenti to WV.' S; Henry, 1.1,'334,900,'idated l March 23, 1920, or as shown iin my fprionPat- Ventf1,713,494, fdated Maylet, 11929. :rllh-iscross` protectionl 'relay P, 1 as :diagrammatieal'lyf `illustrate'd comprises '.a.; coil or winding adapt- :f ed, when energized with current :of one` polar- 40 ity, to attractfan larmature for releasing a fspring actuated Contact '66'to' .open lthe ycircuit L through Sits :cooperating contacts, .1, indica-ted v conventionallyv .as-arrows.

The powersupply for operating thee-witch f 4521' machine SM, being 4controlled by 'the'zleveriL, is furnished by a battery. 114,-onrotherlrsuitable direct current source. To' prevent maintainf ing severe voverload currents iin case ofy shunts Aor the like, suitable overload 'devicesrrnaytbe ff employed, which -inthis specific case'hasibeen Vv shown asL a'fuse J.

VT he switch repeater or. SS lrelaydesignated WTP, is located inthe tower'zandi is'y preferably A-a` threelpositionlrelay of the'two'eelement'. or '55 polyphase 'alternating current type. This 'relayfyl/VP has one off-its Windingsfconveniently Ztermed a local 'e winding 8,: connected vto a transformer 15` energized from thev altervnating Icurrent 'line circuit. Thepthe'ror 'line-phase' windingl :is connected-to the 'corn- Amon return 'wire C' for the f switch! machine kSM `and to a contact 30:.of'the"indication re- Is ponsive "device IR. -Ifiboth'windings ofthe relay WP are energized :with-alternating 4cur- "f Tent, suitably :displaced :intime-phase, -a congoverning the relay WP, for indication purposes,- lor' the i lilre. No particular arrange- *mentioff circuitsig-overnedby the relay NP 'has been shown, but it may be assumed th at v*thecontact'ngerf16' of.y this relay TP in its normaland'reverse positions controls thf.` indicationsof the signalsgoverning tra-thc over the-switch TS.

0pcwzz,z'0n-.-'l`1he` voperation of they witch aima'icliine-ITS-Miis controlled by the` movement "-fthelleverl in the Usual way. It is con- 'templated'thatithe operation of the switch machine SM would be44 safeguarded by a lever` -lockgroute locking, detector track-circuit con- `trolparrd the lile, infaccordance with estab- -f'li'shedpra'cti-ce; :but it is lunnecessary to e3;-

plain these features, which are familiar to i'thoselslril-le'd 2in the .art.

The parts and circuits,-'as 'shown in Fig. 1 of the' drawings, arenin thenormal Vconditions --lexistingfavlien theleverL. is in the normal position, :fand l the Vswitch machine "SM an d `svv'itchlipoints TSS arenin the normal position and locked. l/Vith the parts in this normal 'crm'ditioin the line-phase vwinding of the relay `NVPfis energized'fby the-local transformer 9 at ytl-ie-switeh, over-a circuit including the fre'verseoperatingwire 5R and the common returirwire C. whichfcircuit .is traced as fol- 'lowsz-from thefriglit hand terminal of the secondary.of'transformer 9, through the series resistance 1.0, wirer:20,:"fixed contact 21, movableI contact block 7,`fixed Contact 22, wire '123,-'reverse operatingiwire R, fixed contact :24,1movablecontactil, fixed Contact 25, wire 26 and 27, fixed contact 28, movable contact 29,? fixedV Contact 30, ywire 31line-phase i YEndrin'fglrfof frelayVPgiwires32 and 33, Winding f-of 'polarized relay I'P,`-wire 34, 'common wire -C,'wires"35 andfG;y fixed `contact 37, movable contactfblloclif, fixed `contact 38, wire 39, through the left hand terminal of the second- -aryf'of the transformer v9.

`-'Although the yarmature .A and the 'field Iifwindirrg1F ofthe:switchlmachine motor are connectedacross the-secondary of the trans- 'former9 over wire.20,1lfiXed lcontact 2l, movablev' cont-acti block7, r fixed iconta'ct 22, wires 23 iand 45,1 fixedf'contacte, movable ycontact f-fblock '6,`i-Xed contact .47, ,wires Sfand 49, ar-

mature A, wire 50, fiXed:contact51, movable indication responsive device IR is connected` iu multiple with the line-phase winding 4 of the relay TP over'wires 32, 44 and 57, coil 56 of indication responsive device IR, wires 58 and`27, fixed contact 28, movable contact 29, fixed contact 30, and wire`31, this coil 56 has such ai high impedance to'alternating current, that a sufcient voltage drop is maintained for supplying operating current to said line-phase winding 4 of'relay VP.

Thus, with-the switch TS and its-control lever L in the normal position, the switch repeater relay TVP is energized, as shown, so as to establish through the normal contacts of the relay WP such signal control circuits, or the like. as may be found expedient to obtain the desired protection.

1f the switch points TS are unlocked or shifted from the normal position, forV any reason, due to hand operation, or a cross or ground, the point detector contacts PD open the circuit above traced for venergizing the line-phase winding 4 of the relay WTP, and the contact finger 16 of this relay VP asfsumes its neutral or deenergized position,

putting to stop the signals governing the traffic over the switch TS in question, or otherwise safeguarding train movement over such a switch which is not locked, or out of i correspondence withits control lever L.

If the switch machine SM should be cranked by hand, or otherwise caused to assume its reversed locked position, and even though the point detector contacts PD are closed in the reverse position, the line-phase winding 4 of the relay WP is not energized, because the switch machine SM and switch points TS are out of correspondence with the position of the control lever L. This is because the reverse energizing circuit for the relay VVR'includingl the point detector contacts PD closed in the reverse position, is over the normal operating wire N, throughthe reverse lever contacts 77 and 78, and the reverse contacts and 87 of the indication responsive device IR, both of these contacts being opened with the lever L in the normal position.

Villien the lever L is manually shifted from the normal position to the reverse position, a reverse operating circuit is established a,

follows from the positive terminal of battery 14 through wire 59, fuse J, wires 60 and 61, fixed contact 62, movable Contact 12, fixed contact 63, wire 64, reverse operating wire .wire C, wire 65, contact 66, wire 67 to the opposite terminal of battery 14.

As soon as the lever L ismoved from the normal position, the` normal energizing circuit for the line-phase winding 4, of the relay VP is broken at the normal lever contacts 24 and 25, so that the relayvVVP is at once deenergized, putting the signals to stop, or vthe like. As soonas the switch machine SM isunlocked, the point detector contacts PDare shifted to the intermediate or open circuit position, making another break in the normal energized. circuit for the line-phase winding 4 of the relay NVP, so that this relay WP remains d'eenergized even though the ylever L should be returned to its normal position. Thus, as soon as the switch machine SM is operated from its normal locked position, the relay W'P is deenergized.

After the switch machine SM completes g its operation to the reverse position, due to direct current power beingsupplied toits reverse operating circuit, the movable contact blocks 5 and 6 of the pole changer contacts PC are automatically shifted to thev C, wire 34, winding of cross protection relay P, wires 33, 44 and 73, reverse operating coil V74 of indication responsive device IR, wires 75 and 76, fixed contact 77, movable contact 13, fixed contact 78, wire 79, normal operating wire N, fixed contact 80, movable contact block 6, fixed contact 81, wires 82 and 50, to the opposite terminal of the armature The dynamic indication current, fiowing for a short interval after the switch machine SM has completed its operation, energizes the reverse coil 74 of the indication responsive device IR, shifting its contact 29 from the normal position shown to the reverse dotted line position, thereby establishing a reverse energizing circuit for the line-phase winding ofthe relay WP, which circuit may be traced as follows, bearing in mind that the lever L is now in the reverse position and the point detector contacts PD'are closed in the reverse position from the right hand terminal of the secondary of transformer 9, through series resistance 10, wires 20 and 83, fixed contact 84, movable contact 8, fixed Contact 85, wires 86 and 35, common wire C, wire 34, winding of polarized relay P, wires 33 and 32, line phase winding 4 of relay WP, wire 31, fixed contact 30, movable contact` 29,

ltlieindication responsive device IR 4must have operated its contact to the reverse position, .and this in-'turn occurs only if the fixed contact .87 ,wires 88iand 76,' lixed'contact '77, -movable contact 13, fixed coi-itact'78,rwire -79,faiorinaloperating` wire N, wire"S9,f:fiXed contactl 90,;.movable contactfblock 7, fixed :contact 91, lwires'92 and 39,: tothe opposite .terminal ofthe secondary .oftransformer 9.

The operation of the switch'fivoinithefreaverse to the normal position is similar to that Idescribed involving similar circuits, and need not be described in fdetail. l:

Thus, if the switch machine SM has operated'properly to move the-switch points,has locked up, and vlias'transniitted va dynamic indication) current through the cross-protection relay.` P, the relay WP isagain energized., :but with such instantaneous relative polarities in the local and line-phase windings,'tliat `vthe contact 1G `assumes the' reverse position.

It will be evident that, before the'relayWVP can thus be energized to the reverse position,

cross-protection circuit through the crossprotection relayP is intact to permit the `iiow ofdynaniic indication current through the reverse operating vcoil 74 of saidaindieation responsive `device IR.

In this way, the integrity of the cross-pro tect-ionf circuit is checked at they end of each authorized or normal operation, and :it is-assuredA that the cross-protection relay I Pland -its circuit connections, protecting the' switch machine SM against improper operation by crosses,` is in condition tofunction before' the 'Jai rclaylVl? isvenergized to permit the clearing offsignals governing traffic overthe switch ln this connection, it should be understood l that an SS relay, controlled in the usual manner over va-r separate polarized circuit, assures that the switch is over `Iand locked in the proper:position,before the signal can be cleared. `4Such an SS relay-will also'actto put the signals to stop, if the switch is improperly operated by cross orf-otherwise, from Aits. existing position outy of correspondence witlizits control lever. :Sucharan SSrrelay,

whowever, does not prevent operation 'off the switch mach-ine by a` cross-or the like, after atrain has'accepted the signalfand while ltlietra-in'is. passing over the switch. 'Such protection is afforded hythis inventiombecause in addition to the continuing indication of switch position` by the relay WR'the crossprotection relay P and its circuit connections,

which are checked upon each operation, prevent such an improper operation ofthe switch :machine Aby cross, in .thewell known finanner.

:For example, if acrossshould 'occur 7between 'the control wires NfiaiidsR, the current tend- ,fingto operate the switch 1machine 1 would -have-a pat-h through the cross protection 4re- -la-y `inea zdirect'ion; to'. openi its contacts 66 emoties VIKandLibrea-k .the common rreturn connection from.I the i switclif :machine imotor.

ilt-should :be notedfthat ,the-.yenergizaten of the relay VPfto move its Contact linger-16 to a new position is dependentxnot only nipoti,

thel .point :detector-'contacts .f PD, .operated in accordance a with 1 the position :off the switch points TS and their --flockedxcondition, but also upon the dynamic indicationcurrent, so

that the operation .of the relayWP toanewj" position shows :that the:;sw'itch ,pointsTS have been: :operatedwover iandrlookedup .by power in .the usualwauthorize'dway,f.ratlier :tha-n mere-ly. that: thezswitohpoints TTS are over and locked in a: certain position. :.T'hiso affords :a Vdesirable additionalcheck upon .the

proper and. normal' operati-on. of: the system. lFor example Y if theoi eratorf should move the i P lever L to thereverse positiomand the switch machine for some =reason-should;- fail to g5 respond, and then was opei-'ated :by :hand to not I be/ energized. since "there had been ,-no

dynamic indication current f transmitted i'throughthe reversecoil 74 of, the indication.,

responsive ydevice i IRito .moveits Contact 29 into a position corresponding Withthe:` lever contacts and coin-pietethe reverse. energizing vcircuit for :the frelay WR .'Ifhus, feven through the leven L .andswiitch machine .SM would :be ini corresponding jpositions -funcler the conditions assumed, the -fact=that ythis f condition was biiouglitfaboiit .by .anabnormal neutral. or "open .,position, current .tends to iiow through thefseoondaryof the. transformer, `and. if sufficient value .ofdirect current -flows in the secondary, the'core of thistransformer x9 becoinesJr-inagnetized .above satura.-

tion,.which destroys the reactanceof the .pri-

#mary toa,degreethat.mightzinjure .itoiblow fuses intheprimary circuit. .Also, without tnisfseries resistance .10, the secondary .ofthe transformed.9-w0uldact .toshunt theoperating current from. the motonat .the `beginn-ing of .the operationnnd Ypriontogthe shiftingof the point :detectorcontactsffPD. lTl'iisseries resi stance. l0 is-talso :desirablebecausethe sec- ,oiidary `of the. transforment) is. ..in.mul.t iple with the next operating coil ofthe indication responsive .deviceIB,.across. the. armature.` A

and field F of the motor, so that, if. Ythis resistance1 were not. .used,: the. low ohniicv resistance of the secondary. ofthis transformen) -.v

would interfere with the proper. energization of Ithe coils 56 .and 74,.by1the ldynaniioindicw tion. current. If.i.,desared,..atcondensermay bezused .in lieuii thisseries resistance 10. A

. resistance ,11 is prefeizably @used in .series with the primary of the transformer 9, so as` to obtain more economically the desired voltregulation and operating characteristics of this transformer 9 over the varying line wire resistances, due to the varying distances between the switches and tower.

Fig. 2 shows a modification in which additional normal and reverse coils 100 and 101 respectively, are employed for the indication responsive device IR, these coils 100 and 101 being included in the connections, as shown,

between the battery 14 and the lever contacts'- 68 and 62 through which normal and reverse operating current is supplied respectively.

`With the parts in the normal position, as

shown in Figs. 1 and 2, both of theseadditional coils 100 and 101 are deenergized, the circuit through the reverse coil 101 being broken at the lever contacts 62 and 63 and the circuit through the normal coil 100 being broken at the contacts and 81 of the pole changer PG. V

When the lever L is shifted to the reverse position, the operating current in thereverse operating circuit flows through the addi' tional coil 101 and holds the Contact 29 ofthe indication responsive device'IR in its normal position, so that any stray current applied to the normal operating wire N, due to a cross i' or the like. even though such stray current may How through the reversel operating coil 74, will not operate the Contact 29 while motcr operating current is flowing.

Also, if the operator, after having moved the lever L to the reverse position,should return it to the normal position, the flow of current in the normal operating circuit, established due to the reversable characteristics of the switch machine SM, as more fully eX- plained in the Howe Patent 1,466,903, abovev mentioned, would iiow through the Aadditional coil 100 and operate the vcontact 29 to a reverse position, breaking the normal energizing-circuit for the relay WP, and preventing its energization until'the dynamic indication current for operation ofthe indication responsive device IR, energizes the coil 56 of the device IR and restores the contact 29 to the normal position. In this way, the integrity of the cross-protection circuit is checked after a partial operation of the switch machine SM, as well as after each complete normal operation.` In other words, if the switch machine SM should be partially operated iu one direction, and then reversed in midstrolre. in accordance with the'modi- Vfication in Fig. 2, the dynamic indication current would have to How again before the relay NP would be energized, thereby checking the cross-protection circuit after such a partial operation of the switch machine SM, as well as at the end of a complete operation, as in Fig. 1. y

ldlhile it is desirable, in order to economize` in the amount of wire between the tower and the switch machine, to control the switch repeater relay WP over the same wires used;

limiting resistance 10; and these point de t'ector contacts are connected to separate line wires 93 and 94, running from the switch machine SM to the tower, and connected respectively to the line-phase winding 4 of the relay WP, through two eXtra pairs of lever contacts 95-96 and 97-98 included in the normal Vand reverse positions of the lever. The contacts 28 and 87 of the indication responsive device IR are connected by wires 102 and 103 to the lever contacts 96 and 98.

This modification of Fig. 3 operates in the same manner as above explained in connection with the embodiment of Fig. 1, with the energizing circuits for therrelay WP in Fig.

3 beinfr readily` traced by analogy to those 0f rig. i.

From theforegoing it can be seen that j thereis provided by this invention a switch repeater or SS relay, which not only affords a continuous indication of the positionand locked condition 'of the track switch points, but also serves to check the integrity of the cross-protection circuit after each operation, said SS relayalso assuming anew operated position, only if the switch machine and lever Vare in correspondence as vthe result of a normal or lauthorized power operation. The invention also provides for the control of this SS relay over the regular switch machine operating circuits, although it should be un-y derstood that this SS relay may be controlledin` other ways, andl over a separate pair of wires as shown in Fig. 3, without departing from the features of the invention characteristicl of the use of the indication .responsive device IR, in combination with lever contacts;

While certainspecific embodiments of the invention have been show-n and described, it should be understood that these particular constructions and arrangements of parts andl circuit are susceptible to considerable modiication and adaptation in practice, without departing from the invention, its characteristic,features,and advantages.

Having. Vdescribed my invention, I now claim 2,-

1. In an interlocking system for railroads,

a track switch,v a switch machine for operating said switch, a control -lever,'two control wires anda common return wire connecting said'lever and said switch machine, anelectroresponsive means operable to different positions to indicate the 'posit-ion of the switch points of said switch and having normal and wires anda common return wire between said switch and -said leverprovidi-ng -normal and reverse operating'- circuits l for sai-d switch machine, an dmeans -or indicating Ithe cond-itionof f'said switch `machine -operablebyalternatingV current flow-ing in 'normal and' .re-A

verse energizing circuits respectively, includ- "ing said operating circuits of'the switch ma- 3? In an interlockingsystem -for railroads, v a track switeh, a'lswit'ch" machine for operatingsaid switch, acont-rol lever," two control wires and" a l common* return`- wire between'- said switchr and said Ylever yprovidingnormal an d reverse operating circuits for 'said switch machine, a three position' relay in the Y, tower responsive only to current 'distinctive from' the current vfor operating" saidA switch.V` machine and having normal and reverse energiz# ingl "circuits each including. respectively' one.

ofsaid control -wires .and said common -re' turnl wire.

if Inan'interlocking systemv tor railroads, a 'track" switch, ai switch machine for operati ing said switch', a control lever, .two controlV wires and aA common return'v wire between saidA switchi :and said lever-providing normal ,and v revelerse'operating circuits 'for said switch ma'-l chine, a relayin the tower,v normal Aand reverse energizing circuits. torsaid relay 1n'- cludi'ng respectively, one y of-- said controlwiresand said commonreturn .wire, and. contacts associated with'said switch' orfsupplying alternating currentto'sai'd energizing cii'- cuits'ofoppositeinstantaneous polarity whenswitch' points'are'over and locked in their eX- treme positions.

5.'I In an interlocking system for railroads,x.

an electrically*operatedswitch machine, a control lever having normal and 'reverse con'- tacts, a relayin the "tower having normal and reverse .energizing circuits including said. le-l ver contacts, and means responsive to indication current 4generated. dynamically-,by saidfv switch-machine after operationthereof for.l controlling said energizing .circuit for said relay.

6. Inan interlckingsystem for railroads, anv electrically "operated switch machine, aY control lever having normal and reversecontacts",` aA relay in ',thle'tower having normal and reverse energizing circuits. an indicationv responsive device energized by indicatori current generated' dynamicallyl by said i switch maehfine'after'each operation thereof for clos: mginormal fand reverse contacts :respectively included 2in1 the fene'rgizing circuits for.` said relay, .and meansf operatedvloy-l said!y leverY fori opening' and closing the energizing circuits for said relay.

7i In an'interlocking system for railroads, an" electrically operated switch machine, a control-lever having normaL and: reverse contacts, a three positionzrelayin the tower havinglnormal and'reverse energizingv circuits respectively including said normal and reverse=levercontacts, and 'means operated by dynamic indication: current produced by said switchumachine for alternately closing said circuits; Y

8.-' Inf an interlocking system for-railroads, a control lever, a'distant switch machine havingsnormal'andireverse operating wires governed by-said control lever, a contact means controlled by dynamic indication current received over said' normal and reverse operating wires alternately, a three position relay, and means operable-fte control said three-position relay in accordance with said distant switch including said contact means.

lnf'an interlocking system for railroads, acontrollever in-y an interlocking tower, a distant switch` machine, two control wires andaicommon return wire connecting` said controlfflever with said switch machine, a relay in' saidV` interlocking tower responsive onl-y'-v t-o current distinctive trom the current.' capable Obperating said switch machine and operable to either of three positions, and means, including one of said two control wires with said common return wire,

Voperable Ito control-said relay to one of its three positions,land means,` including the other of said two control wires with said common return wire, operable to control said -relayto another of its three positions.

10.`In an interlocking system for railroads, afcontrol lever, a distant switch machinefhaving'norin'al and reverse operating wires-governed by said lcontrol lever, a dead beat armature controlled'by dynamic indication current received over said normal Vand reverse operating wires alternately, a threeposition relay, and means operable to control saidfthree-position relay in accordance with-said distant switch machine including Vsaifdnormal" and reverse operating wires alternately used, and contacts operably controlledby said dead beat armature.

ll. In an interlocking system for railroads, a Y control* lever, a distant switch machine `having-normal'and reverse operating wires,

governedby 'saidfcontrol lever, tivo electromagnetic coils, a dead beat armature being controlled to one'ot'two vextreme positions by energization` o-f`either one of said electro magnetic coils, means operably controlling energization 'of said electro magnetic coils bydyn'amic current'supplied 'from said distant switchmachinc over said normalL and rcversc operating wires alternately, a relay capable of ,assumingv anyone of three positions, .andmeans operable to control said relay to a particular position including, said normal and reverse operating wires alternately used, and contacts operably controlled by said dead beat armature.

12.7In an interlocking system for railroads, a control lever, a distant track switch controlled by a switch machine, two operating wires connecting said control lever with said distant switch machine, an electro responsive means indicating the position of said track switch, and means operably controlling said electro-responsive means including` said two operating wires alternately used, contacts operated by said control lever, and contacts operably controlled by dynamic current received from said distant switch machine.

13. In an interlocking system for railroads, a control lever, a distant track switch controlled by a switch machine, two operating wires connecting said control lever with said distant switch machine, an alternating current relay capable oi assuming any one oft three positions and indicating the positions assumed by said distant track switch, and means operably controlling said alternating current relay including, said two operating wires alternately used, cont-acts operated by said control lever, and contacts op erably controlled by dynamic current received from said switch macnine. Y

14. In an interlocking system, the com bination with a distant track switch, a distant operating switch machine, a control lever for said switch machine, and an `indi cation selector having coils included Vin the dynamic indication circuit of said switch machine, of an alternating current relay, contacts governed by the condition of said indication selector, and means opcrahly controlling said alternating current relay, with said means including, contacts controlled by said control lever, and said contacts governed by the condition of said indication selector.

15. In an electricl interlocking system, the combination of a switch machine, a normal and a reverse control circuit for said switch machine, a normal and a reverse indication circuit for said switch machine, an indication responsive device, a three-position alternating current relay, means operably controlling said indication responsive device over said normal or reverse indication circuit, and means operably controlling said three-position alternating current relay over said normal or reverse indication circuit after said indication responsive device has been operably controlled in response to a completed operation of said switch machine.

1G. In an interlocking system for railroads, a control lever, a distant track switch controlled by a switch machine, two control wires connecting said control lever with said distant switch machine, an alternating current relay capable of assuming either of two eX- treme positionsk in correspondence with said distant track Yswitch in one of two eXtreme positions, and capable of assuming a deenergized position .upon movement of said distant track switch from an extreme position, and means operably causing said alternating current relay to assume a position in correspondence with said distant track switch, including, contacts jointly operated by said distant track switch and said switch machine, said two control w" 1es alternately used, contacts operated by said control lever manually controlled, contacts operably controlled by dynamic indication direct current received over said two control wires alternately used.

17. In aninterlocking systemlior railroads, a track switch, a switch machine controlling said` track switch and being operated over normal and reverse operating wires in conjunction with a common return wire, a transformer localk to the track switch, a series resistance in the primary circuit of said transformer, a series'resistance in the secondary circuit of said transformer, and point detector contacts jointly operated by said track switch and said switch machine for alternately connecting said secondary circuit of said transformer to said normal or reverse operating wires and said common return wire, having opposite instantaneous polarities when said switchis over and locked in eX- treme positions.

18. In an interlocking system for railroads of the dynamic indication type as shown and described, a track switch controlled by a switch machine, a control lever having normal and reverse contacts, and electro-responsive means in the tower indicating the position of said track switch and having normal and reverse circuits including said normal and reverse contacts respectively, and normal `or reversev contacts respectively operablyk controlled by direct current dynamic indication current from said switch machine. 19. In an interlocking system, a distant switch machine, a normal and a reverse control circuit :t'or said switch machine, a normal and a reverse indicat-ioncircuit from said switch machine, an indication responsive deviceihaving normal and reverse coils included respectively in said normal and reverse indication circuits and having normal and reverse coils included respectively in said normal andreverse control circuits, an electro-responsive device indicating the position of said switch machine, and means operably controlling said electro-responsive device for a given indication condition including, said normal or reverse indication circuit, and contacts operably controlled by said indication responsive device. Y

20. In aninterlocking system for railroads, a track. switch, a switch machine for operating saidswitch, Lt-control lever, two

control wires.and..a connnon=.=retarn wire connecting said lever...andfsaid switchmachine, an electroxrespons'irve. means operable tov dilierent positionsto indicatethe position of ythe switchpoin'ts.,.ofxsaid switch and having n-ormal and reversefenergizing circuits, .each respectively:including onel of said .control'wireszand said common return wire, kand each established only. if `said lever and said switch machine assume corresponding positions.

2l. In an interlocking system for railroads, a track switch, a switch machine for operating said switch,` a controlleven'two control wires and a common return wire between saidswitch and. said lever providing normal and4 reverse ioperating circuits for said switch machine, and: means. for indicating the condition of said switch machine operable. by alternating current .ilowing in normal and reverse indicating circuits respectively, one. ofsaid indicating circuisincluding one control-wire and .said common wire and the. otherV indicating circuit including the other control wire'and said common wire.

22, In -an .interlockingsystem for railroads, a4 track switch, a. switchmachine. for operating .sai-d` switch, .acontrol lever, a three position relay Iin the tower having normal and reverse energizing` circuitseach including respectively one of said control wires and said commonreturn wi-reand contacts closed only when. said lever and switchassumed corresponding positions.

23. In an interlocking system.; for .railroads, a controlle-ver, a-.distant'switch machine having normaland reverse voperating wires, a dead beat .armature controlled` hy dynamic indication. current received over said normaland reverse operating wires alternately, a three-position relay,` and .means operable to control said three-position relay in accordance-with-said distant switch machine .includingA said normal and reverse operating wires alternately used, and alsoincluding contacts operably controlledby said dead beat armature.

2i. In an interlocking system for railroads, the c-ombinationfwith a distant' track switch, cfa switch machine. for controlling said trackl switch; a lever; a normal wire, a reverse wire and a common wire connecting said lever and switch machine; a normal circuit for operating said switch machine including said normal wire: and said common wire; a reverse circuit for operating said switch `machine including said reverse wire and said common wire; indicating means at said lever controlled over two distinctive circuits each circuit including a contact of said lever, a contact operated in accordance with the switch points of said track switch and a contact closed only. in response todynamic IVADE H. REICHARD. 

